Abstract
Oxide dispersion strengthening(ODS)is an effective method to improve the mechanical properties of Mo-based materials.However,the mechanical properties of traditional ODS-Mo composites are always lim-ited by the coarsening and intergranular distribution of second-phase particles.In this work,an effective nano-reinforcement dispersion strategy was developed to fabricate an ODS-Mo composite with ultrafine grain and intragranular distribution of second-phase particles.Core-shell structural Mo nanocomposite powders,with internally distributed sub-10 nm Al2O3 dispersoids,were prepared by nano atomization doping(AD)followed by a chemical vapor transport growth strategy.Then,ODS-Mo composites with ultra-fine Mo grain(below 700 nm)and high-density intragranular κ-Al2O3(below 20 nm)nanoparti-cles were prepared via spark plasma sintering(SPS),in which a coherent interface between κ-Al2O3 and Mo matrix was formed.The composites present remarkably improved hardness(above 500 HV),bend strength,and compressive yield strength(above 1664 MPa)at room temperature,with a suitable strain to fracture of 27.1％.The calculation of strengthening mechanisms indicates that the enhancement was mainly attributed to the intragranular κ-Al2O3 nanoparticles.This nano-sized reinforcement distributed within the grain can more effectively pin dislocations and achieve dispersion strengthening in ODS-Mo composites.Therefore,this strategy can efficiently construct intragranular second-phase nanoparticles and open up new avenues to fabricate high-performance ODS-Mo composites.
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